1. Field of the Invention
The present invention relates to communication terminal equipment which perform data communication with party terminals whose data communication rates are different from those of the caller terminal equipments and more particularly, to a communication terminal equipment of a simple structure, which allows data communication with any party terminal having a data communication rate different from that of the caller terminal equipment.
2. Description of the Related Art
Recently, integrated services digital network (ISDN) and the corresponding various sorts of data exchange networks connectable with the ISDN have become widely available, and various types of terminals have been used in these networks. Data communication has been increasingly carried out between these different types of terminals.
In the data communication between these different types of terminals, it sometimes occurs that the data communication rate of a terminal is different from that of another terminal. In such a case, matching of the data communication rate among terminals must be made by changing the data communication rate of at least one terminal.
Referring to FIG. 3, an ISDN 200 is connected with a terminal 101 having a data communication rate of 64 Kbps and also with another data exchange network 300 which in turn is connected with another terminal 102 having a data communication rate of 56 Kbps. Data communication between the terminals 101 and 102 can be established by means of interwork between the ISDN 200 and the data exchange network 300. The data communication is required to be carried out at the data communication rate of the terminal 101 of the ISDN 200 which is smaller than that of the other terminal, that is, at 56 Kbps.
For data communication between different types of two terminals, a matching circuit must be provided for matching of their data communication rates. In the case where a plurality of party terminals each have different data communication rates, different matching circuits must be provided depending on the data communication rates and be selectively used as necessary, thus involving a complicated circuit configuration and a high cost.